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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#define TRACE 0
#define ERRORS 1
#define LONG long
#define WORD short
#define WORDS 2048
/*───────────────────────────────────────────────────────────────────────────│─╗
│ The LISP Challenge § 8086 PC BIOS / x86_64 Linux System Integration ─╬─│┼
╚────────────────────────────────────────────────────────────────────────────│*/
#define ATOM(x) /* a.k.a. !(x&1) */ \
({ \
char IsAtom; \
asm("test%z1\t$1,%1" : "=@ccz"(IsAtom) : "Qm"((char)x)); \
IsAtom; \
})
#define OBJECT(t, v) /* a.k.a. v<<1|t */ \
({ \
__typeof(v) Val = (v); \
asm("shl\t%0" : "+r"(Val)); \
Val | (t); \
})
#define SUB(x, y) /* a.k.a. x-y */ \
({ \
__typeof(x) Reg = (x); \
asm("sub\t%1,%0" : "+rm"(Reg) : "g"(y)); \
Reg; \
})
#define STOS(di, c) asm("stos%z1" : "+D"(di), "=m"(*(di)) : "a"(c))
#define LODS(si) \
({ \
typeof(*(si)) c; \
asm("lods%z2" : "+S"(si), "=a"(c) : "m"(*(si))); \
c; \
})
#define REAL_READ(BASE, INDEX, DISP) /* a.k.a. b[i] */ \
({ \
__typeof(*(BASE)) Reg; \
if (__builtin_constant_p(INDEX) && !(INDEX)) { \
asm("mov\t%c2(%1),%0" \
: "=Q"(Reg) \
: "bDS"(BASE), "i"((DISP) * sizeof(*(BASE)))); \
} else { \
asm("mov\t%c3(%1,%2),%0" \
: "=Q"(Reg) \
: "b"(BASE), "DS"((long)(INDEX) * sizeof(*(BASE))), \
"i"((DISP) * sizeof(*(BASE)))); \
} \
Reg; \
})
#define REAL_READ_ARRAY_FIELD(OBJECT, MEMBER, INDEX, DISP) /* o->m[i] */ \
({ \
__typeof(*(OBJECT->MEMBER)) Reg; \
if (!(OBJECT)) { \
asm("mov\t%c2(%1),%0" \
: "=Q"(Reg) \
: "bDS"((long)(INDEX) * sizeof(*(OBJECT->MEMBER))), \
"i"(__builtin_offsetof(__typeof(*(OBJECT)), MEMBER) + \
sizeof(*(OBJECT->MEMBER)) * (DISP))); \
} else { \
asm("mov\t%c3(%1,%2),%0" \
: "=Q"(Reg) \
: "b"(OBJECT), "DS"((long)(INDEX) * sizeof(*(OBJECT->MEMBER))), \
"i"(__builtin_offsetof(__typeof(*(OBJECT)), MEMBER) + \
sizeof(*(OBJECT->MEMBER)) * (DISP))); \
} \
Reg; \
})
#define REAL_WRITE_ARRAY_FIELD(OBJECT, MEMBER, INDEX, DISP, VALUE) \
do { \
__typeof(*(OBJECT->MEMBER)) Reg; \
if (!(OBJECT)) { \
asm volatile("mov\t%0,%c2(%1)" \
: /* manual output */ \
: "Q"((__typeof(*(OBJECT->MEMBER)))(VALUE)), \
"bDS"((long)(INDEX) * sizeof(*(OBJECT->MEMBER))), \
"i"(__builtin_offsetof(__typeof(*(OBJECT)), MEMBER) + \
sizeof(*(OBJECT->MEMBER)) * (DISP)) \
: "memory"); \
} else { \
asm volatile("mov\t%0,%c3(%1,%2)" \
: /* manual output */ \
: "Q"((__typeof(*(OBJECT->MEMBER)))(VALUE)), "b"(OBJECT), \
"DS"((long)(INDEX) * sizeof(*(OBJECT->MEMBER))), \
"i"(__builtin_offsetof(__typeof(*(OBJECT)), MEMBER) + \
sizeof(*(OBJECT->MEMBER)) * (DISP)) \
: "memory"); \
} \
} while (0)
static void *SetMemory(void *di, int al, unsigned long cx) {
asm("rep stosb"
: "=D"(di), "=c"(cx), "=m"(*(char(*)[cx])di)
: "0"(di), "1"(cx), "a"(al));
return di;
}
static void *CopyMemory(void *di, void *si, unsigned long cx) {
asm("rep movsb"
: "=D"(di), "=S"(si), "=c"(cx), "=m"(*(char(*)[cx])di)
: "0"(di), "1"(si), "2"(cx));
return di;
}
static void RawMode(void) {
#ifndef __REAL_MODE__
int rc;
int c[14];
asm volatile("syscall"
: "=a"(rc)
: "0"(0x10), "D"(0), "S"(0x5401), "d"(c)
: "rcx", "r11", "memory");
c[0] &= ~0b0000010111111000; // INPCK|ISTRIP|PARMRK|INLCR|IGNCR|ICRNL|IXON
c[2] &= ~0b0000000100110000; // CSIZE|PARENB
c[2] |= 0b00000000000110000; // CS8
c[3] &= ~0b1000000001011010; // ECHONL|ECHO|ECHOE|IEXTEN|ICANON
asm volatile("syscall"
: "=a"(rc)
: "0"(0x10), "D"(0), "S"(0x5402), "d"(c)
: "rcx", "r11", "memory");
#endif
}
__attribute__((__noinline__)) static int PrintChar(LONG c) {
#ifdef __REAL_MODE__
asm volatile("mov\t$0x0E,%%ah\n\t"
"int\t$0x10"
: /* no outputs */
: "a"(c), "b"(7)
: "memory");
return 0;
#else
static short buf;
int rc;
buf = c;
asm volatile("syscall"
: "=a"(rc)
: "0"(1), "D"(1), "S"(&buf), "d"(1)
: "rcx", "r11", "memory");
return rc;
#endif
}
static void PrintString(char *s) {
char c;
for (;;) {
if (!(c = REAL_READ(s, 0, 0))) break;
PrintChar(c);
++s;
}
}
static int XlatChar(LONG c) {
if (c >= 'a') {
asm volatile("" ::: "memory");
if (c <= 'z') c -= 'a' - 'A';
}
return c;
}
static int EchoChar(LONG c) {
if (c == '\b' || c == 0x7F) {
PrintString("\b \b");
return '\b';
} else {
PrintChar(c);
if (c == '\r') {
PrintChar('\n');
}
return c;
}
}
static noinline int ReadChar(void) {
int c;
#ifdef __REAL_MODE__
asm volatile("int\t$0x16" : "=a"(c) : "0"(0) : "memory");
#else
static int buf;
asm volatile("syscall"
: "=a"(c)
: "0"(0), "D"(0), "S"(&buf), "d"(1)
: "rcx", "r11", "memory");
c = buf;
#endif
return EchoChar(XlatChar(c));
}
/*───────────────────────────────────────────────────────────────────────────│─╗
│ The LISP Challenge § LISP Machine ─╬─│┼
╚────────────────────────────────────────────────────────────────────────────│*/
#define TYPE_ATOM 0
#define TYPE_CONS 1
#define ATOM_NIL 0
#define ATOM_T 8
#define ATOM_QUOTE 12
#define ATOM_ATOM 24
#define ATOM_EQ 34
#define ATOM_COND 40
#define ATOM_CAR 50
#define ATOM_CDR 58
#define ATOM_CONS 66
#define ATOM_LABEL 76
#define ATOM_LAMBDA 88
#define ATOM_SET 102
#define ATOM_DEFUN 110
#define Quote(x) List(ATOM_QUOTE, x)
#define List(x, y) Cons(x, Cons(y, ATOM_NIL))
#define Caar(x) Car(Car(x)) // ((A B C D) (E F G) H I) → A
#define Cdar(x) Cdr(Car(x)) // ((A B C D) (E F G) H I) → (B C D)
#define Cadar(x) Cadr(Car(x)) // ((A B C D) (E F G) H I) → B
#define Caddar(x) Caddr(Car(x)) // ((A B C D) (E F G) H I) → C
#define Cadr(x) Car(Cdr(x)) // ((A B C D) (E F G) H I) → (E F G)
#define Caddr(x) Cadr(Cdr(x)) // ((A B C D) (E F G) H I) → H
#define BOOL(x) ((x) ? ATOM_T : ATOM_NIL)
#define VALUE(x) ((x) >> 1)
struct Lisp {
WORD memory[WORDS];
unsigned char syntax[256];
unsigned char look;
char token[16];
WORD globals;
int index;
char str[WORDS];
};
const char kSymbols[] aligned(1) = "\
NIL\0T\0QUOTE\0ATOM\0EQ\0COND\0CAR\0CDR\0CONS\0LABEL\0LAMBDA\0SET\0DEFUN\0";
#ifdef __REAL_MODE__
static struct Lisp *const q;
#else
static struct Lisp q[1];
#endif
static void Print(LONG);
static WORD GetList(void);
static WORD GetObject(void);
static void PrintObject(LONG);
static WORD Eval(LONG, LONG);
static void SetupSyntax(void) {
q->syntax[' '] = ' ';
q->syntax['\t'] = ' ';
q->syntax['\r'] = ' ';
q->syntax['\n'] = ' ';
q->syntax['('] = '(';
q->syntax[')'] = ')';
q->syntax['.'] = '.';
q->syntax['\''] = '\'';
}
forceinline WORD Car(LONG x) {
return REAL_READ_ARRAY_FIELD(q, memory, VALUE(x), 0);
}
forceinline WORD Cdr(LONG x) {
return REAL_READ_ARRAY_FIELD(q, memory, VALUE(x), 1);
}
static WORD Cons(WORD car, WORD cdr) {
int i, c;
i = q->index;
REAL_WRITE_ARRAY_FIELD(q, memory, i, 0, car);
REAL_WRITE_ARRAY_FIELD(q, memory, i, 1, cdr);
q->index += 2;
c = OBJECT(TYPE_CONS, i);
return c;
}
static void SetupBuiltins(void) {
CopyMemory(q->str, kSymbols, sizeof(kSymbols));
q->globals =
Cons(Cons(ATOM_NIL, ATOM_NIL), Cons(Cons(ATOM_T, ATOM_T), ATOM_NIL));
}
static char *StpCpy(char *d, char *s) {
char c;
do {
c = LODS(s); /* a.k.a. c = *s++; */
STOS(d, c); /* a.k.a. *d++ = c; */
} while (c);
return d;
}
static WORD Intern(char *s) {
int j, cx;
char c, *z, *t;
z = q->str;
c = LODS(z);
while (c) {
for (j = 0;; ++j) {
if (c != REAL_READ(s, j, 0)) {
break;
}
if (!c) {
return OBJECT(TYPE_ATOM, z - q->str - j - 1);
}
c = LODS(z);
}
while (c) c = LODS(z);
c = LODS(z);
}
--z;
StpCpy(z, s);
return OBJECT(TYPE_ATOM, SUB((long)z, q->str));
}
forceinline unsigned char XlatSyntax(unsigned char b) {
return REAL_READ_ARRAY_FIELD(q, syntax, b, 0); /* a.k.a. q->syntax[b] */
}
static void GetToken(void) {
char *t;
unsigned char b;
b = q->look;
t = q->token;
while (XlatSyntax(b) == ' ') {
b = ReadChar();
}
if (XlatSyntax(b)) {
STOS(t, b);
b = ReadChar();
} else {
while (b && !XlatSyntax(b)) {
if (b != '\b') {
STOS(t, b);
} else if (t > q->token) {
--t;
}
b = ReadChar();
}
}
STOS(t, 0);
q->look = b;
}
static WORD ConsumeObject(void) {
GetToken();
return GetObject();
}
static WORD GetQuote(void) {
return Quote(ConsumeObject());
}
static WORD AddList(WORD x) {
return Cons(x, GetList());
}
static WORD GetList(void) {
GetToken();
switch (*q->token & 0xFF) {
default:
return AddList(GetObject());
case '\'':
return AddList(GetQuote());
case ')':
return ATOM_NIL;
case '.':
return ConsumeObject();
}
}
static WORD GetObject(void) {
switch (*q->token & 0xFF) {
default:
return Intern(q->token);
case '\'':
return GetQuote();
case '(':
return GetList();
}
}
static WORD ReadObject(void) {
q->look = ReadChar();
GetToken();
return GetObject();
}
static WORD Read(void) {
return ReadObject();
}
static void PrintAtom(LONG x) {
PrintString(q->str + VALUE(x));
}
static void PrintList(LONG x) {
PrintChar('(');
PrintObject(Car(x));
while ((x = Cdr(x))) {
if (!ATOM(x)) {
PrintChar(' ');
PrintObject(Car(x));
} else {
PrintString(" . ");
PrintObject(x);
}
}
PrintChar(')');
}
static void PrintObject(LONG x) {
if (ATOM(x)) {
PrintAtom(x);
} else {
PrintList(x);
}
}
static void Print(LONG i) {
PrintObject(i);
PrintString("\r\n");
}
__attribute__((__noreturn__)) static void Reset(void) {
asm volatile("jmp\tRepl");
__builtin_unreachable();
}
__attribute__((__noreturn__)) static void OnUndefined(LONG x) {
PrintString("UNDEF! ");
Print(x);
Reset();
}
__attribute__((__noreturn__)) static void OnArity(void) {
PrintString("ARITY!\n");
Reset();
}
#if !ERRORS
#define OnUndefined(x) __builtin_unreachable()
#define OnArity() __builtin_unreachable()
#endif
/*───────────────────────────────────────────────────────────────────────────│─╗
│ The LISP Challenge § Bootstrap John McCarthy's Metacircular Evaluator ─╬─│┼
╚────────────────────────────────────────────────────────────────────────────│*/
static WORD Atom(LONG x) {
return BOOL(ATOM(x));
}
static WORD Null(LONG x) {
return BOOL(!x);
}
static WORD Eq(LONG x, LONG y) {
return BOOL(x == y); /* undefiled if !ATOM(x)||!ATOM(y) */
}
static WORD Assoc(LONG x, LONG y) {
for (;;) {
if (!y) OnUndefined(x);
if (Eq(Caar(y), x)) break;
y = Cdr(y);
}
return Cdar(y);
}
static WORD Append(LONG x, LONG y) {
if (x) {
return Cons(Car(x), Append(Cdr(x), y));
} else {
return y;
}
}
/**
* Gives list of pairs of corresponding elements of the lists x and y.
* E.g. pair[(A,B,C);(X,(Y,Z),U)] = ((A.X),(B.(Y,Z)),(C.U))
* @note recoded to make lists in dot notation
* @note it's zip() basically
*/
static WORD Pair(LONG x, LONG y) {
if (!x && !y) {
return ATOM_NIL;
} else if (!ATOM(x) && !ATOM(y)) {
return Cons(Cons(Car(x), Car(y)), Pair(Cdr(x), Cdr(y)));
} else {
OnArity();
}
}
static WORD Appq(long m) {
if (m) {
return Cons(List(ATOM_QUOTE, Car(m)), Appq(Cdr(m)));
} else {
return ATOM_NIL;
}
}
static WORD Apply(long f, long a) {
return Eval(Cons(f, Appq(a)), ATOM_NIL);
}
static WORD Evcon(LONG c, LONG a) {
if (Eval(Caar(c), a)) {
return Eval(Cadar(c), a);
} else {
return Evcon(Cdr(c), a);
}
}
static WORD Evlis(LONG m, LONG a) {
if (m) {
return Cons(Eval(Car(m), a), Evlis(Cdr(m), a));
} else {
return ATOM_NIL;
}
}
static WORD Set(LONG e) {
WORD name, value;
name = Car(e);
value = Cadr(e);
q->globals = Cons(Cons(name, value), q->globals);
return value;
}
static WORD Defun(LONG e) {
WORD name, args, body, lamb;
name = Car(e);
args = Cadr(e);
body = Caddr(e);
lamb = Cons(ATOM_LAMBDA, List(args, body));
q->globals = Cons(Cons(name, lamb), q->globals);
return name;
}
static WORD Evaluate(LONG e, LONG a) {
if (ATOM(e)) {
return Assoc(e, a);
} else if (ATOM(Car(e))) {
switch (Car(e)) {
case ATOM_QUOTE:
return Cadr(e);
case ATOM_ATOM:
return Atom(Eval(Cadr(e), a));
case ATOM_EQ:
return Eq(Eval(Cadr(e), a), Eval(Caddr(e), a));
case ATOM_COND:
return Evcon(Cdr(e), a);
case ATOM_CAR:
return Car(Eval(Cadr(e), a));
case ATOM_CDR:
return Cdr(Eval(Cadr(e), a));
case ATOM_CONS:
return Cons(Eval(Cadr(e), a), Eval(Caddr(e), a));
case ATOM_DEFUN:
return Defun(Cdr(e));
case ATOM_SET:
return Set(Cdr(e));
default:
return Eval(Cons(Assoc(Car(e), a), Evlis(Cdr(e), a)), a);
}
} else if (Eq(Caar(e), ATOM_LABEL)) {
return Eval(Cons(Caddar(e), Cdr(e)), Cons(Cons(Cadar(e), Car(e)), a));
} else if (Eq(Caar(e), ATOM_LAMBDA)) {
return Eval(Caddar(e), Append(Pair(Cadar(e), Evlis(Cdr(e), a)), a));
} else {
OnUndefined(Caar(e));
}
}
static WORD Eval(LONG e, LONG a) {
#if TRACE
PrintString("->");
Print(e);
#endif
e = Evaluate(e, a);
#if TRACE
PrintString("<-");
Print(e);
#endif
return e;
}
/*───────────────────────────────────────────────────────────────────────────│─╗
│ The LISP Challenge § User Interface ─╬─│┼
╚────────────────────────────────────────────────────────────────────────────│*/
void Repl(void) {
for (;;) {
PrintString("* ");
Print(Eval(Read(), q->globals));
}
}
int main(int argc, char *argv[]) {
RawMode();
SetupSyntax();
SetupBuiltins();
PrintString("THE LISP CHALLENGE V1\r\n"
"VISIT GITHUB.COM/JART\r\n");
Repl();
return 0;
}